I think that you could achieve this by defining an event that repeats (say, every 10 minutes). This should be an Auto Event so it would get attached to every Change Order. The event would use a condition that you define to test the Scheduled End Date and Status. The Event actions would include a Multi-Notification macro to the Affected End User.
The problem with this solution is that the Event would continue repeating and that as long as the condition is met then the user would get another notification.
A more sophisticated and effective way to handle this would be to develop a Process Automation Manager (PAM) process.